The 21/7 contraceptive pill regimen is 'outdated' and taking combined oral contraceptives without a 7-day break is the '21st century way to take the pill', according to Professor John Guillebaud.

Breakthrough ovulation is most likely to occur in women who inadvertently lengthen their pill-free interval by forgetting to take the first or second pill of a new pack. | GARO/PHANIE/SCIENCE PHOTO LIBRARY

Professor Guillebaud, emeritus professor of family planning and reproductive health at University College London, told the RCGP annual conference in Liverpool last week that the recommendation to take the pill on a 21/7 regimen was made 60 years ago and was ‘based arbitrarily on the calendar, and not on science’.

A study published in the British Journal of Family Planning (n=120) found that half of women aged 18 to 30 years taking a low-dose oral contraceptive with a pill-free interval had quiescent ovaries on the seventh pill-free day. However, in 23% of women, pre-ovulatory follicles were present.

These follicles can readily reach sizes leading to ovulation if the pill-free interval is inadvertently lengthened by the woman forgetting to take the first or second pill of a new pack.

Further information

Not only does this occur commonly but women are also more likely to have intercourse during this time, after abstaining during the withdrawal bleed. These two factors increase the risk of contraception failure and unintended pregnancy.

Taking pills continuously affords a greater margin of error as most women will be able to miss up to seven pills and still be protected against pregnancy, even if they had sex in that week, said Professor Guillebaud. This has the further benefit of reducing the need for emergency contraception.

More effective contraception

A patient leaflet recently adapted by Professor Guillebaud advises women that taking the pill on a 365/365 schedule is an off-licence indication but is backed up by a large amount of evidence and is supported by medical authorities in the UK and WHO.

It advises women that continuous use makes the pill more effective as a contraceptive, and reduces problems such as period pain, PMS and migraine. Continuous pill-taking also eliminates the inconvenience of the monthly withdrawal bleeding, which Professor Guillebaud said has ‘no known health benefits’.

Women who still want to have a regular ‘period’ could consider taking the pill on a 84/4 schedule, where three packets are taken back-to-back followed by a pill-free interval of 4 days.

Professor Guillebaud told the GP audience: ‘Good learning requires some unlearning – I want us to unlearn the idea that the combined pill is a good method of contraception: it is not – if it is taken on a 21/7 regimen'.

‘We argue for substituting improved regimens that do not intermittently cease to provide full ovulation suppression’.